Disputes over land, resources and women have a long history of spawning fisticuffs, and the proof is written on men’s faces. A new theory suggests that our male ancestors evolved facial features specifically designed to take a punch.

Researchers found that facial bones commonly broken during a slugfest grew more resilient as time progressed — especially those of our australopith ancestors (the immediate predecessors of the human genus Homo). The reinforced bones were also the same bones that showed the most divergence between males and females, further supporting the “protective buttressing” theory.

The findings challenge a long-held hypothesis that attributed the appearance of beefy faces of early hominids to the need to chew hard-to-crush nuts. The current findings, in contrast, suggest that violence was an evolutionary force behind face structure.

Nuts or Punches?

University of Utah researchers David Carrier and Michael Morgan combined ancient fossil data with observations of modern injuries from fistfights. Jawbones were most frequently broken, along with cheek, eye and nose structures, the BBC reports. These specific bones were the same bones that grew more massive in male australopiths, but not in females.

Based on the same researchers’ prior findings, the evolution of reinforced faces coincided with changes in early humans’ hands that allowed for the formation of a fist. Further, recent discoveries looking at wear patterns on hominids’ teeth suggest they didn’t have an exclusively nut and seed diet, discounting the theory that hard-to-eat foods spurred changes in bone structure.

“Together these observations suggest that many of the facial features that characterize early hominids may have evolved to protect the face from injury during fighting with fists,” Carrier said in a news release.

Humans’ Violent Past

Morgan and Carrier received criticism for their original finding regarding fists, and they told the BBC that they expect their current findings to illicit a similar response. The lynchpin of the controversy is an ongoing debate about whether humans were once peaceful creatures, or if violence has always been fundamental to our species.

“The debate over whether or not there is a dark side to human nature goes back to the French philosopher Rousseau who argued that before civilization humans were noble savages; that civilization actually corrupted humans and made us more violent,” Carrier said in the news release. “This idea remains strong in the social sciences and in recent decades has been supported by a handful of outspoken evolutionary biologists and anthropologists. Many other evolutionary biologists, however, find evidence that our distant past was not peaceful.”

How would more beefier (or more “resilient”) face bones have conferred a reproductive advantage (so that evolution can favor it)? While it might be nice to have jawbones that can take a slug, if it doesn’t result in more children, either through a survival selection or sexual selection, then it doesn’t spread in a population. Isn’t it more likely that Australopiths just found big-boned faces attractive? We see something like that in human men and women.

Also, human teeth sure seem easy to knock out with a fist, and teeth are pretty important to eating, and therefore surviving, and therefore having lots of children.

Also, just how often did Australopiths have fistfights? Hunter-gatherer humans aren’t all that violent.

Cointelamateur

Beefier face= less open wounds, either through teeth knocked out or broken bones= less earlier death/not attractive to females when dying of infection.

Humans have 32 teeth. That’s plenty in survival to reproduction terms Add in our wisdom teeth too- which may explain why you’d need replacements- not from being stupid and eating rocks.

Why would you believe hunter-gatherer’s aren’t violent? In terms of tribes today? That’s because there aren’t as many opposing tribes looking to rob other tribes after they hunted an animal. Lot easier to take meat from people than to hunt your own. Ditto good land for gathering herbs.

KokoTheTalkingApe

Less infection is good. So why wouldn’t they evolve thicker facial skin, instead of thicker face bones? That would seem less metabolically costly than thicker bones. Anyway, it is probably easier to cut somebody’s skin than break somebody’s bones. Which is what we are talking about, right? Bones?

In animals, loss of teeth is associated with drastically lower survival rates. Same should be true of Australopiths.

Why do I believe human hunter-gatherers aren’t very violent? Because anthropologists have studied them, and measured the violence among them. Of course, humans and Australopiths could have very different societies.

Sarai Pahla

i.e. Teeth are fairly irrelevant in this discussion – the point is who got to “get it in”, as they so nicely phrase it on the Jersey Shore…

KokoTheTalkingApe

I think teeth are relevant, in this way: if face bones evolved to be thicker specifically in response to being punched in the face as Carrier and Morgan claim, why didn’t teeth also become harder to knock out? Teeth are probably more fragile than say, the cheekbone, and are a more plausible target for evolution than the cheekbone, because people who lose teeth would tend to die fairly quickly. Fragile teeth make Carrier and Morgan’s theory seem weaker.

KokoTheTalkingApe

Somehow I saw an earlier post of yours, but it isn’t showing up now. Presumably it didn’t pass moderation. I think you were saying that some humans voluntarily give up incisor and canine teeth, meaning they aren’t very important to humans. Also you said teeth contain enamel, which is the hardest and most durable bone there is.

But my challenge isn’t about either of those. I am saying it seems easier to knock out a tooth in a fistfight than break a cheekbone, with greater consequences. My argument is not that losing a tooth has to have dire consequences, it is that the consequences are at least comparable to breaking a cheekbone. And yet apparently teeth did not become harder to knock out, which is what you would expect under Carrier and Morgan’s theory (that fistfights actually shaped Aust. bone morphology.) But perhaps teeth did become harder to knock out, in parallel with the thicker cheek, eye socket and jaw bones. I don’t know. Did they?

KokoTheTalkingApe

And for that matter, do we know that Australopiths could even punch accurately? Can gorillas and chimpanzees punch? They are terrifically strong, but I know they cannot, for instance, throw a ball accurately. They do not have the brain structures for it for it.

Sarai Pahla

Yes, primates most certainly punch each other and pretty hard too – they are more than capable in that respect. Fighting is the most primal form of combat – why you would question whether Australopithecenes fought truly baffles me…

KokoTheTalkingApe

I am not questioning whether Aust. fought. I am questioning whether they fought with fists against faces often enough, with severe enough consequences, for Aust. to evolve thicker face bones in response.

But primates can and do punch? Is that their typical way to fight? I have seen only hammer blows and ripping and tearing, and even more intimidation and dominance displays that did not come to actual blows.

Anonymous

It is not their brain, but their shoulders that prohibit them from throwing a ball accurately. A human a throw farther and more accurately since our shoulders allow such movement.

KokoTheTalkingApe

Nope. Humans can hit a moving target, even throwing underhand. With practice, we can bring down moving birds and rabbits. No ape or monkey can come close. Our throwing motion requires coordination of various joints and muscles faster than can be done in real time, which means the entire program has to be created ahead of time, and then executed as a kind of Apollo launch.

ReverendMachine

Hominids are also primarily bipedal, which means we use our legs and torso to greater effect when throwing a spear, rock, or punch, especially if done underhanded. Chimps and Apes tend to be off balance when bringing their torsos perpendicular to the ground. The structure of the shoulders, spine, and pelvis for hominids have greater range of motion when upright, this motion is very restricted in apes and chimps. The jaw having gotten smaller also means less surface area upon which to land a fist or hammer punch. Its difficult to say what kind of evolutionary pressures may have been present besides just intrahominid fighting.

KokoTheTalkingApe

“[Bipedalism] would also lead to a more intuitive use of this wider range of motion, that would be absent in other apes and chimps…”

Is this speculation on your part, or is there something behind these thoughts? I have to say, bipedalism as a factor hadn’t occurred to me.

But anyway, the uniquely and cognitively human aspect (that I am proposing) isn’t the force of the throw (and having three times the muscle strength could partially make up for a more awkward stance in apes and monkeys) but the accuracy, and the fact that the complex and lengthy series of motions must be planned in advance.

ReverendMachine

The concept comes from: Darwin’s Legacy: Scenarios in Human Evolution By Sue Taylor Parker & Karin Enstam Jaffe. It talks about the advantages and differences between Apes & Humans with regard to throwing and other aspects of human movement. The planning is definitely a human quality the anticipation and fore thought in setting up an attack is made possible by our superior cognitive abilities, but the actual action is a build up of instinctual reactions built upon by practice. After all it is not the cognitive function that makes humans skilled at throwing but the practice of said action, the improvement over a given period of trial and error. This would ultimately be a useless practice for species such as chimps, monkeys, & apes as they seldomly hunt for nourishment.

KokoTheTalkingApe

And yet another thing: I believe modern humans have more delicate facial bones than Australopiths. Why? Do we fistfight less than they did?

ReverendMachine

The evolution of thicker facial bones could also directly result in the advantage of stronger shoulders with which to break those stronger bones. In Richard Dawkins the Blind Watchmaker, there is a great chapter on continued competitive evolution, within the same species and in adjacent ones. It may have been that what ultimately won out in the evolutionary arms race was something similar to what lions, and other large predators do when they try and intimidate the other to avoid an actually fight which could prove costly.